I've used Heater body suits for many years and they are often the difference in cold weather on being able to stay on stand all day...not to mention being comfortable. They keep you toasty warm and block wind well, too. Tip: I keep my thermos (cocoa) and food inside my HBS near my feet. This keeps the food from freezing (often very cold conditions in northern Minnesota during rifle season) and minimizes scent. Once you try a HBS, you'll wonder why you waited so long (I now have two of them!).